ABSTRACT
A problem of interest in plasma physics, and relevant to laser fusion, is that of determining the nature of unstable waves. When an intense laser light irradiates a solid target surface, the target material is ablated and ionized to form a plasma corona. Plasma responds to external and/or internal electromagnetic field as an active dielectric medium. In particular, an externally applied electromagnetic field (such as from a high power laser beam) can couple to the natural normal modes of the plasma, converting part of its energy to the plasma’s internal energy. For a homogeneous plasma, the maximum growth is approximate. Collisions and/or plasma inhomogeneity introduce a threshold for the instability. The principal parameter in determining the threshold intensity is usually the plasma inhomogeneity. Plasma inhomogeneity limits the region over which these waves can resonantly interact, and propagation of the waves outside this interaction region introduces a dissipation mechanism which has to be overcome by the laser pump.
